Nice approach. Saying "please double check me" removes the stigma of counting. It let's the provider know you care to be correct, are willing to be checked, and avoids misunderstandings later in case one actually did miscount. Gives the provider the chance to count not out of suspicion but at your invitation, and to acknowledge your integrity. Probably makes things more comfortable, which could lead to -- shall we say -- more enthusiastic service. :-)