I don't think so. I almost positive that we got hot dogs the last time we were down there (last Oct) and it was counted as a counter-service meal. Their hot dogs are pretty substantial - not really "snack size".
It never hurts to ask. When we were there, we got DD a Lunchable and they counted it as a snack. We were told, most items under $4 could be counted as snacks. Just check when you are there.
In most cases, items under $4 are a snack UNLESS they are a "meal"-type food (slice of pizza/sandwich/etc). You may have a CM that rings up a $3.95 hot dog as a snack but most would probably call it a CS meal and have you add a drink and dessert to it.
The items that can be purchased with a snack credit are incredibly generous as it is. They are typically marked with the DDP logo on the sign/price list. Just look for it.
Disney has a problem with giving meat protein as a snack. At Pop we were allowed anything as a snack except for bacon or sausauge. Didn't think it was worth $3 for 3 slices of paper thin bacon.