Gisele Bündchen Goes On Vacation with Jiu-Jitsu Teacher, Tom Sources Question Timing

Gisele Bündchen is getting super close to a handsome MMA teacher ... and sources connected to the former couple -- Tom Brady and Gisele, that is -- are questioning the timing.

The guy is Joaquim Valente, a jiu-jitsu instructor who lives in Miami. Gisele has known him for at least a year and a half. She took lessons from him, and then signed her 2 kids up for lessons as well.

Gisele and Joaquim were out to dinner in Costa Rica Saturday, with her kids, Benjamin and Vivian. It's especially interesting, because Tom and Gisele made Costa Rica their vacation spot during the off-season.

Gisele and Joaquim did a super sexy photo shoot together more than a year ago for Dust Magazine ... presumably about the art of jiu-jitsu.

Gisele has posted her fondness for Joaquim's MMA teaching skills, saying it gave her confidence and empowerment.

A source connected to Gisele tells TMZ GB and JV are not dating, noting many friends were present in Costa Rica. The source says there were 6 adults and 8 kids at the get-together.

Another source close to the ex-couple is not buying it, asking why this Miami guy is in Costa Rica with her. This source added, "It always seemed weird she just one day abruptly ended the marriage."

Page Six was the first to report on Joaquim and Gisele.