Yes you are allowed to leave and return according to the rules and it should reset your '6 months' in country time...BUT the thing is any time you pass through ICE they can refuse your entry if they choose.

From what I understand normally there is not a problem but as peoples' experience here has shown you never know these days.

They may ask you your intentions at the first crossing and honestly I don't know if asking then would be a good idea or not...part of me thinks a good officer would be happy to help you and glad you were conscientious...but should you get the jerk it may be better to just be quiet and move along.