No USA today on 10m WSPR?

There were no USA stations spotting my 10m WSPR today.   As I was a bit suspicious of this, I have just reset and resync'd the 10m beacon. All spots were single hop F2 and either F-layer backscatter or "out of season" Es (DK6UG). Even after the resync there were no new 10m spots.

UPDATE 1905z:   I see that G8VDQ (93km) was spotted on 6m again at 1602z.

UPDATE 2210z:   No 10m spots at all since late lunchtime. The 10m WSPR beacon and 6m WSPR are still on and will remain on overnight. This is the first time in many weeks without a single 10m WSPR spot from the USA. Indeed, the only spots were single hop.