I never really thought about it until last night while watching one of the bazillion media links on this, but one woman reporter was there, and actually went onto the bridge and mentioned that if you're not familiar with it, it's not an easy bridge to walk across. She said something to the affect of how it has a lot of missing pieces that you have to really watch where your feet land. As soon as she said that, I watched the BG video again and realized it looks like that's exactly what he was doing. Not that he had a distinct gait, but that anyone walking on that old rickety bridge would also appear to have the same distinct gait, due to the way you have to walk on it, and watch your step.
This has probably been mentioned a million times already, so my apologies if I'm bringing up ancient details that have been discussed at length