Humidity also plays a part in how comfortable they feel, as well as temperature, I don’t know what location you are in, but if you are keeping their cage as cool as possible and it’s normal for them, you’re comfortable etc, then it may not be an issue - I cannot comment though as I don’t know your location.
(I can say that here in my area, humidity and temperatures of 26-30 would be far too much for them and at those temperatures I am taking considerable action to cool them down. Mine are most active and most comfortable at around 18-20 degrees.
My boys are almost three years old and while they aren’t zooming constantly anymore, they are active.)
Having a look at your set up and working out whether it is enriching enough would be a good idea
Does each piggy have enough space? That is a minimum of 120cm x 60cm but if they’ve got more than that then that is much better
Do they get time out of their cage (individually)?
I use hay as bedding everywhere in their hutch (now my two do live in my shed so they also need it for warmth), but they spend a lot of time foraging through the hay and wandering around. I also scatter feed veg and pellets (i don’t use food bowls) so this keeps them occupied looking for other food items amongst the hay. It also means they eat a lotnof hay.
They also have lots of hideys, tunnels, boxes, which they spend a lot of time running through and playing in. I remove any hideys which are too cosy during the day so to stop them from just sitting around in them!
the guides below may help you
Enrichment Ideas for Guinea Pigs
Hot Weather Management, Heat Strokes and Fly Strike