Not to my knowledge intregajosh if any thing they are quicker to show buds.Do bigger plants take longer to flower?
They have normally been vegged for longer so are more mature and most likely already shown sex.
Looking at the pics it looks similar to re-vegging. I would definitely check you lighting if the plants are in a separate groom. Look at the bulb make sure its not blackening if it is change it. When growing with hps always have a spare even if it is a old one. My timer recently was switching my hps off and on i did notice for a while until it done it whilst i was feeding the plants. I changed the timer and bulb and bingo all was good as i always have spare of both these.
Just to check if you have a dimmable ballast make sure you have not turned it down by accident 600w bulbs do not run well at 250w .