Nothing President Obama does regarding this election is “accidental” or by chance.   There is no doubt in my mind he was fully aware of the simultaneous fundraiser taking place within the same hotel.  Heck, I would hypothesize he was not only aware of it, but the campaign probably strategically chose the fundraiser location so he could attend under the auspices of coincidence.  
President Obama would not want the optic of intentional participation, yet he needs to, and wants to, showcase his ideological alignment with the gay community.   So a coincidental opportunity fits the bill nicely and provides a measure of cover.  Its how this crew rolls.
(Beltway Confidential) — President Obama crashed “an LGBT fundraiser” today in Florida at a hotel where he is having his own fundraiser this evening.

Obama “dropped by an LGBT fundraiser to participate in a photo line,” according to the pool reporter. The Democratic National Committee (DNC) and “senior campaign officials” are meeting with about 50 LGBT supporters who paid $2,500-a-piece to hear about Obama’s record on LGBT issues.
Obama’s unwillingness to support gay marriage explicitly has irritated his LGBT supporters, while the White House says that Obama’s position is still “evolving.”  (read more)