If you're asking which is correct, the first one means it has been a long time since you contacted each other and had a chance to exchange updated news/information. "To touch base" is an idiom that means this. Saying "... it has been a while since we touched" means that you want to physically touch the other person in a romantic or sexual way: by eliminating the "base," you are now using the literal meaning of the verb "to touch."

Since we touched不严谨啊，至少也应该是since we got in touch.