Curious about Protocol (patent number on the bottom of our product)

Upon asking the question, "Can I put the patent number on the bottom of our product?" (The product attaches to a shoe and would thereby partially obscure the patent number if the number were inscribed on the bottom of our product) my attorney told me verbatim, "I would not recommend doing that." I say, "OK, thanks." and after hanging up with him, I think about it for a while and realize that I don't see the logic in his recommendation, and then call or email him back asking him to be more specific, am I still on the clock with him or should I be entitled to a more thorough explanation free of charge? My questioning isn't meant to undermine his expertise, just to get more clarity.