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Concur. "Hey, we missed you. Hope everything is ok" sounds courteous not stalker-y. The hard part comes next. If you don't hear from them in reply, write it off as a loss and don't contact them until they contact you. If you do hear from them, you're going to have to accept their reply at face value and not second guess. If you are really questioning their interest level, you might want to wait for them suggest a "rain check" rather than suggesting it yourself. If they say "let's try again" then they are probably interested. If they don't, time to move on.