This is definitely one of those "heads-up" type of alerts that you should read before you simply lock.

If you have not yet seen a positive reprice from the lender in question, there's virtually no chance of a negative reprice.  Even if you have seen a positive reprice, only the jumpiest lenders would be considering a negative reprice.  Even then, it's not a certainty as MBS have only just now fallen an eighth of a point from the mid day highs.  

5.5 coupons are still up 6 ticks (.19) on the day and 10yr yields are still down 4.6bps at 4.333.

The best way to use this alert is as a cue to lock for those who were already planning on locking today and who have already seen a positive reprice.