Too much air space in secondary?

I just transferred a Belgian Tripel IPA to secondary. I started with 5.25 gallon batch, and is now 10.48% (2 weeks in primary). I noticed that there is alot of head space left in the 5-gallon carboy, more than I've had before. I am estimating that I have 4-4.25 gallons within the carboy. I was hoping to be able to leave this in the secondary for about a month or so due to the high ABV, but does this air space pose a problem?

Thanks for your help.

You might need to worry about oxidation here. I would just boil and cool a small amount of sugar and add it to the secondary. The CO2 produced during the fermentation of the sugar should drive off the O2 present in the head space of the secondary.

I have used a 6-gallon carboy for my secondary about 8 batches - all of which were 5 gallon batches, and have never ended up with oxidation. I held a porter in there for about 6 weeks, and it has no off flavors at all. The yeast will still give off a little CO2, which is heavier than regular air, so it will form a "protective layer" on top of the beer. Adding a small about of sugar water like toman8r suggest would also help this layer form.

Edit: From the Homebrew Wiki: Oxidation
"The most significant cause of oxidation is hot-side aeration, which occurs when air is mixed into the wort at temperatures above about 80 degrees F. At that temperature, aldehydes are formed in the wort which are not degraded by later boiling and which remain in the finished beer. These aldehydes will gradually result in an oxidative character as the beer is stored."

So, it seems to me that if you are holding the beer at lower temps (as you should be anyway) there is minimal concern.

well when you racked the beer released some CO2 which will protect your brew. if your worried you can fill the headspace with more CO2 yourself. get a block of dry ice, about a pound will do. break it up and put a chunk in some warm water. now pop the stopper on your carboy and pour the fog and only the fog into the carboy. keep this up for about a minute or so then recap the carboy while still pouring the fog. the fog/CO2 will be trapped inside the carboy and protect your brew.

I make 5 gallon batches, and use a 6 gallon carboy all the time for seconday fermentation. I have never had a problem with oxidation.