Her performance, in an event won by Finland's 19-year-old European cross- country champion Annemari Sandell, was less good than she had been expecting only two weeks after running the fastest road 10km this year, 31min 41sec, on a testing course in Cooperbridge, North Carolina.
But, as her third London Marathon looms on Sunday, the 31-year-old Scotswoman says she feels fitter than she has for four years. Hence her ambivalent mood. "You know me," she said with a little smile. "I'm never happy unless I'm winning."
In setting out on the flat, looped course by the seafront, she had indeed looked as lean and hungry as the world champion McColgan of 1991 - hair scraped up into a cascading top-knot, eyes Oriental above jutting cheekbones, elbows working rythmically from side to side.
On the last of the five loops, however, she lost contact with Sandell, and Ireland's Catherina McKiernan, after stumbling at a turn. The final gap was not huge - McColgan finished in 15min 18sec, five seconds adrift of the Finn - but she could not increase her pace.
"I was a bit disappointed," she said. "I thought I was going to do better. But maybe I was asking a bit too much of myself to think I could come in and run away from these people. Because of the training I'm doing, I think 5km is a bit short for me now."
She drew comfort from the fact that her two rivals had geared their recent efforts to the cross-country season, while her efforts - between 110 and 130 miles a week throughout the winter - had been geared towards running 26 miles 385 yards.
That preparation has gone more smoothly than in recent years, a fact reflected in her relaxed appearance. "I am confident," she said, lolling back in her chair. "When you are running well you actually start looking forward to racing. Before the last London Marathon I was actually dreading it because I knew that I wasn't fit enough to do it. But I feel really healthy at the moment. I've done a lot of hard training and this is the pay-off."
Would she, someone ventured, care to give any predictions for Sunday's race? She pursed her lips and shook her head several times. The old assumptions, the old arrogance, have been tempered by experience. But the old determination is still clearly evident.
"I am going into the race with the attitude that I will do whatever it takes to win. I'm in shape to run a personal best if I need to - although 2:27 is not that tough a PB. But I have never actually run what I should be running for marathons."
The same could be said for Paul Evans, who marked his recent return from altitude training in South Africa by taking second place in the men's 5km behind Kenya's former world junior cross-country champion, Philip Mosima.
Evans, who improved his personal best by a second with 13:48, was satisfied with finishing ahead of two of his main rivals for a British Olympic marathon place on Sunday - Gary Staines, who was fifth in 13:59, and the 1993 winner, Eamonn Martin, who was eighth in 14:05.
"Training has been going well," Evans said. "But I wanted to perform well here so I can go to the starting line on Sunday knowing I am fit. Now I feel a purpose has been served."
Martin was also happy after what was his first 5km race in two years. "This was just a matter of blowing the lungs out and getting the legs turning over quickly," he said.