I wouldn't worry about it if you only put such a small amount , No way your going to clog the heater core . I personally dont use that type of product at all .
That's an old rumour from many ,any years ago.
no its not gonna hurt anything, especially if u used a small amount i have seen heater cores get clogged from using stop leak but only when people go crazy and pour a very very large amount into the radiator, u will be fine dont worry.
Aluma^Seal, or any so-called sealer is temporary at best, if it works at all. It usually stops up the cooling system causing more damage. You will eventually have to repair the leak, but after using the sealer, you will also, at the very least, have to replace the radiator and heater core.
It will be cheaper in the long run to just fix the problem right.
Any of those so-called sealers will clog up your cooling system. They should outlaw it, or at least put a warning on the label like cigarettes have.
I know, I used it once, and it wound up costing me almost $1600 to get my cooling system completely replaced.