I received a similar email this morning as well. The prices fluctuate between weeks and with individual ships and itineraries based on capacity sold by a certain time. This will be a "General" price increase effective March 22nd. for June, July, and August sailings.
The rates have been unbelievably low for so long now. With more demand finally returning this is to be expected. They don't usually announce rate increases with such a wide spread media and email blitz though. They are probably testing the waters so to speak, or making a marketing effort to drive bookings.
is a link to a WSJ article.
Thanks Tim C, for posting this. You beat me to it.