As stated this will be tuff! The bird could have lost interest Or saw something it did not like. did yo ahve decoys out? If not the and as you said you are smack dab in the middle of a big Flat hayfield. The bird got nervous cause it did not see what is talking........OR

Now one thing you must be made aware of - even though your blind has shoot through screen mesh windows - and IF you had them all open and the mesh down with 360 degree coverage - you could have created a SHADOW - while in the blindand that is what the bird saw! some not normal movement.

Remember - there is still light passing through the screen. Always leave on area in the blind with a black no back filter light at all. In fact the darker the better is my motto........

Want to prove this theory - set your blind up - pull the mesh down but leave all sides open and have your budy sit in there. then have him move - waht do you see? And you will see shadows!

JW