A little well-meaning direction is a great move. How else will you know how to get her off? But, if it goes down the "my ex used to do this" avenue, she's taken a wrong turn. No man enjoys being given pointers based on the last guy (who, by the way, was WAY more successful at pleasuring her).

The considerate woman leaves out the names and pronouns and says, "I'd like it if you touched my ass more," rather than saying, "John used to do this thing with my ass that drove me nuts. Why don't you try that?" More orgasms for her, less ego bruising for you.