I have no clue what he means. He said it all the time when I was at CU, but it would be at random times so you couldn't really use context to figure out the meaning...For example: he would sometimes pop in the shower after practice and yell "check your instruments"; he would often say it when you would expect him to say "see you later" or "nice talking to you" at the end of a conversation. One time I had a great lr at rollinsville. He came up to me, gave me big hug, and whispered in my ear "check your instruments". He definitely said it during, before, or after races as well.
Some surmised he was just crazy. I still hold on to the belief that there is meaning behind the phrase, and cling to the idea that it is possible to figure out what that meaning is.
-ag