Absolutely nothing to worry about. A few notes:

1. Active fermentation can certainly die down after 2-3 days.
2. Airlock bubbles do indicate active fermentation. A lack of airlock bubbles does not necessarily indicate a lack of active fermentation. CO2 is sneaky - it can get out a lot of places besides through your airlock liquid.
3. 70F is getting on the warm side for most yeast strains. Fermentation will produce heat of its own, meaning your beer could be several degrees warmer. It won't ruin your beer, but could produce undesirable flavors from the yeast.

So relax and let it roll for a week or so before you take a hydrometer reading to see how far fermentation has actually progressed. Checking the gravity is the only reliable way to know how fermentation is progressing.

Absolutely nothing to worry about. A few notes:

1. Active fermentation can certainly die down after 2-3 days.
2. Airlock bubbles can indicate active fermentation. A lack of airlock bubbles does not necessarily indicate a lack of active fermentation. CO2 is sneaky - it can get out a lot of places besides through your airlock liquid.
3. 70F is getting on the warm side for most yeast strains. Fermentation will produce heat of its own, meaning your beer could be several degrees warmer. It won't ruin your beer, but could produce undesirable flavors from the yeast.

So relax and let it roll for a week or so before you take a hydrometer reading to see how far fermentation has actually progressed. Checking the gravity is the only reliable way to know how fermentation is progressing.