Four of my Japanese teachers are, as you would expect, Japanese, and they all speak English fluently. But now and then, there will of course be slip ups: I often see small grammatical errors in one sensei's handouts. They don't affect the quality of the communication, but is it appropriate to point out these errors to the sensei?

I know that if I was in Japan, I would always want for native speakers to correct me if I made a mistakae; more so in the written form. However, this particular sensei has been at my uni for something like 20 years, and her English is perfect in all other regards; I wonder if it wouldn't be a little insulting to point out otherwise negligible written/spoken errors. Nonetheless, I'd like to know what some teachers think.