convert ALL Grain Recipe to BIAB

[Ozwald]

I doubt you had a problem with tannin extraction, provided the temp readings were accurate. My first guess on your OG issue was actually a stirring issue. Once you're done with your mash (BIAB or traditional) stir the wort up really well. When you think you've stirred it enough, stir it a bit more. If you did it correctly there should be no difference, no matter if you pulled your wort from the bottom or the top.

[santamarina]

Be careful with the strike water temp. If you're looking at an all grain recipe the suggested temp is designed for a traditional water:grain ratio. In a traditional mash you'll only have a few gallons of water (as opposed to 7+ gals for BIAB), so the grain will have more affect on the water temp. The danger with starting too high is that you can kill off some of the enzymes that work at lower temps. If you're using software it should tell you the correct strike temp. If not, aim for about 5F lower than the recipe calls for and you should be in the neighborhood. After having this problem myself, I started with my strike water at my desired mash temp, and once the grain was all in I fired the kettle to get up to where I needed. Just be sure to keep the grain off the bottom of the kettle so you don't scorch it, and keep string while you add heat so the temp stays even through the entire volume of liquor.

[patterns]

Johnnysoj,
The original gravities listed by recipes is what the gravity should be after all the boiling. Your recipe was for a 5 gal finished volume, but if I'm reading correctly you mashed your grains and then took a gravity reading. This gravity reading should be less than the stated original gravity because it has the final amount of sugars but a larger volume of water, so it is diluted. Once you boil all that wort the water evaporates and concentrates the solution so as you boil the gravity increases.
If you have brewing software they usually have some sort of boiloff calculator in them that you can play with. If you aren't using software there are online tools you can find.
I'm using a calculator online and it is showing if you wanted a post boil original gravity of 1.052 with a volume of 4.5 gallons and you are starting with a preboil volume of 6 gal (which is probably close to what you have after you pull the bag out and some water stays with the grain) you would need a preboil gravity of 1.039.