I'm curious too, though I have no stake in shipping any pairings. A while back, I saw an uncited claim on a fansite that in "Dark Glass" (the third season episode that was supposedly "too dark" and got scrapped), Rattrap was supposed to kiss Dinobot - not necessarily romantically, but there you have it. I tried looking for any semblance of a source quote, official backup, etc, to it, since that would have been a rather big deal for a cartoon in 1999, but I couldn't find anything then, and I don't have the time to do an in-depth Google search now.
I don't know if that helps jog any memories for you or anything about where you heard this from.