I don’t know if there is a similar saying in English, but in Italy we say:
A caval donato, non si guarda in bocca
In English we say the same thing ("don't look a gift horse in the mouth"), but we probably shouldn't in any language: I think you'll find that the etymology of that phrase can be traced back to ancient Troy. Stay vigilant!

Interesting, the saying is also used in Romanian. The Romanian form, translated in English, is "Don't check the teeth of a horse given as gift" -- of course, it has same meaning as the one mentioned above. It's very interesting to observe how language evolved so differently yet common expressions can be found in so many of them, although they don't have same origin. We could think that Romanian, as being a Latin language (maybe most close to Latin excepting Italian?), may have more common expressions with Italian (which is the
child of Latin language). Yet this expression also exists in English, which is a Germanic language. I really find this very interesting.
And there are many similar cases. For example, the English sayings "Don't put the carriage before the horse" or "Not seeing the forest for the trees" also exist in Romanian and also in very same form.
Other than that, congrats for receiving your prize, dear fillippone! I am very happy for you and I hope you will show us a photo after you frame the art print
