In this case, Mountain Dew was only able to be purchased at the US Camp, so yes, a listener would know that someone would go from a known position (e.g. my camp) to another known position (e.g. US Camp). Feel free to think out an example suiting your situation better. If you use truly random call signs that's great, in my experience it was more common to re-use your particular squads regular callsign. So no, I'm not talking about an assault from the inside of a camp. Another classic is when a radio guy wants to give his pals a heads-up that some high ranking officer is about to show up in 20 minutes so they should dress up properly.
My main point is that perhaps you are an awesome guy who do better than the average private Schmoe, but in general what you describe sucks from a security perspective.