Index Bounds not getting correctly used

Mongo > db.test.find()
{ "_id" : ObjectId("519ef9b9099b3346085145af"), "c" : 1, "d" : 1 }
{ "_id" : ObjectId("519ef9bc099b3346085145b0"), "c" : 2, "d" : 2 }
{ "_id" : ObjectId("519efa29099b3346085145b3"), "c" : 2, "d" : [ 3, 4, 5 ] }
{ "_id" : ObjectId("519efec6099b3346085145b5"), "c" : 3, "d" : [ 3, 4, 5 ] }

Mongo > db.test.ensureIndex({ d : 1, c : 1 })
Mongo > db.test.find({d : 4, c : {$gte : 1, $lte : 2}}).explain()   // check index bounds, not as expected
{
    "cursor" : "BtreeCursor d_1_c_1",
    "isMultiKey" : true,
    "n" : 1,
    "nscannedObjects" : 1,
    "nscanned" : 1,
    "nscannedObjectsAllPlans" : 1,
    "nscannedAllPlans" : 1,
    "scanAndOrder" : false,
    "indexOnly" : false,
    "nYields" : 0,
    "nChunkSkips" : 0,
    "millis" : 0,
    "indexBounds" : {
        "d" : [
            [
                4,
                4
            ]
        ],
        "c" : [
            [
                1,
                1.7976931348623157e+308     // $lte is not applied
            ]
        ]
    },
    "server" : "bdvlpabhishekk:27016"
}
----------------------
Mongo > db.test.find({d : 4, c : {$lte : 2, $gte : 1}}).explain()   // $lte and $gte is interchanged, but index bound is again not expected
{
    "cursor" : "BtreeCursor d_1_c_1",
    "isMultiKey" : true,
    "n" : 1,
    "nscannedObjects" : 1,
    "nscanned" : 1,
    "nscannedObjectsAllPlans" : 1,
    "nscannedAllPlans" : 1,
    "scanAndOrder" : false,
    "indexOnly" : false,
    "nYields" : 0,
    "nChunkSkips" : 0,
    "millis" : 0,
    "indexBounds" : {
        "d" : [
            [
                4,
                4
            ]
        ],
        "c" : [
            [
                -1.7976931348623157e+308,   // $gte not applied
                2
            ]
        ]
    },
    "server" : "bdvlpabhishekk:27016"
}