Yup, start worrying. Sounds like you've got a leaking rear heater core.
Order a new one, along with possibly a bleeder and new valve from BD or
Vanagain and have go at it - plenty of how tos in the archives. You can
wait, but I think the last thing you want it an interior filled with coolant
(messy, messy stuff). BTW- had to do this last year just after getting my
van. Simple process which took only a couple lazy hours, including removal
and reinstallation of the rear seat.

john

> No really, I've had my 85 westy for about a 18 months now and I parked for
> all of the snow up here in PA for about 2 months total, Well today when I
> cranked her up, and she cranked right up I might add, and turned on the rear
> heater I got a wiff off coolant, not from the front but from the rear, the
> smell went away, but this is the first time I have used the heater and am
> wondering if I should be worried?
> any help appreciated
> WADE