This COULDA been super awkward ... but Alex Rodriguez apparently played it cool when his girlfriend reconnected with her billionaire ex-husband last night ... at an event PACKED with powerful nerds.
Of course, A-Rod is dating Anne Wojcicki -- who was married to Google co-founder Sergey Brin until they split in 2015.
But it seems they're on good (or at least decent) terms because they didn't just hang out at the event last night ... they teamed up on stage and addressed the crowd at one point during the awards ceremony.
