Should I tell my doctor I got gastric sleeve?

We all hate to be judged, so your concern is perfectly reasonable.  It's also true that most docs outside the bariatric community still believe (incorrectly) that weight control is a matter of personal choice rather than primarily a matter of biology, so you might get negative feedback no matter what your weight qualifications would be.
Nevertheless, you really should still tell your doctor about the Sleeve operation for 2 reasons:
1)  A healthy doctor-patient relationship depends on full disclosure and transparency, as a matter of principle.  As the patient, your end of the bargain is to share information without any gaps.  Your doc's end of the bargain is to work with that information in a constructive and objective manner; he may not fully agree but nor should he be judgmental.
2)  Your planned Sleeve operation will cause significant changes in your physiology.  At the very least, you have mild reductions in the normal absorption of Iron and B12.  Unless you plan on having the Mexico surgeon follow up on your physiology in the long run (usually not part of their business plan), your doc is the best bet.

Who knows, maybe your doc will surprise you and be fully supportive.  Most experienced bariatric surgeons in the U.S. agree that the improving risk profile of bariatric surgery makes it reasonable to perform bariatric procedures for well-informed patients with BMI down to 30, although it will likely be some years before insurance companies agree to cover surgery for anyone with a BMI < 35.

Best of Luck!
Dr JP
San Antonio

Thanks for you questionIs good your doctor know about the surgery  even if it`s for a check up, Make a surgery is you decision and your doctor cant decide for you, and he cant judge you, but his job is togive you some advises about the surgery and the risks if you don`t feel comfortable with your  doctor i think you should look for someone else.Dr. Pablo 

If you can't be honest with your doctor, find another one with whom you can.  By the way, you may be interested to know that the American Society for Metabolic and Bariatric Surgery has revised their guidelines for surgery; they now advocate surgery for BMI as low as 30.  Does that mean that insurance will pay?  No.  But it means that you aren't crazy to have surgery at a lower BMI.