jam traffic on monday ?
that's new ...

I would say that they went all back to work

but this will not answer it this time. Can be just a one-off: let's monitor how this continues. It would seem strange after all, unless
new people are awakening their dormant coins.

It's reducing back downwards in size now. The mempool size won't alter the price, it's been far above 10MB before and the price stayed steady. We all know you only have to pay a higher fee for fast confirmations if the mempool is bigger than normal. The mempool's size doesn't frighten us.
